By Prof. Dr.Gehad elnahri

Medical treatment of Glaucoma


Medical treatment is the main line of therapy in POAG

It is contraindicated; as long term therapy, in
1)Congenital glaucoma
2)Any closed angle glaucoma whether primary or secondary

In the core of successful long term therapy are the following factors
1)Efficacy of medication; no further progression
2)Adherence by patient to therapy; directly related to understanding, culture, economy and quality of life under medication

So when prescribing a glaucoma medication you should know the relative efficacy of each
-PG analogues; the strongest, average reduction of IOP is 30-33%
-All other, single medications, reduce IOP by 20-25%
-Only fixed combinations of 2 drugs may be equivalent to PGs
-Adding other drugs to PGs does not produce summation of efficacy by produces a further 10-15% reduction
Medical treatment Glaucoma attachment.php?attachmentid=3269&d=1506708102

PROSTAGLANDINS
Advantages
-efficacy
-better adherence (once daily)
-minimal systemic side effects
Disadvantages
-frequent hyperemia which is a problem in hot countries with frequent VKC, females dislike it.
-change of color of iris and lid margin skin
-Price; double any other medication
Use PGs unless patient cannot afford or hyperemia is marked or persistent
PGs work by increasing the uveoscleral flow, the seepage of aqueous through the ciliary body into the supraciliary space by changing the fluidity of stromal GAGs
PGs favor uveitis and are not the best medications in eyes susceptible to uveitis (postoperative, NVG, herpetic...) or in eyes with ME (diabetic retinopathy)

B-BLOCKERS; you know a lot about them, they decrease aqueous production, are tue best tolerated topically, cheap, efficacy 20%
Disadvantages:
-bronchial asthma; beware
-heart block and heart failure
-short term escape
-long term tolerance

CARBONIC ANHYDRASE INHIBITORS-topical
-decrease aqueous production too, efficacy 20%, with timolol 25-30%
-frequent stinging, allergy not rare
-plz do not combine with oral carbonic anhydrase inhibitor (cidamex) they are useless then
-fixed combination useful in secondary and postoperative cases when PGs are contraindicated

ALPHA AGONISTS--brimonidine
-acts on presynaptic alpha receptor
-mechanisms of action in glaucoma not all clear
-efficacy 20%
-can be combined with others and fixed combination with timolol (25%)
-allergy frequent esp. after 1 year
-useful postoperative and uveitis glaucomas

How to proceed
1)consider patient and systemic condition
2)consider past history
3)how much reduction IOP you need
Start PG unless patient is poor--give timolol
PG reach maximum effect in 3-4 weeks, timolol may loose efficacy in 3-4 weeks (short term escape), i usually prescribe then re-evaluate in 3 weeks
If disc damage is advanced do not start timolol, if patient is poor do surgery, he needs 40%+ IOP reduction
In early and moderate cases you need 30-40% reduction IOP, PG may be sufficient
Eg. Initial IOP 32, 30% reduction is 10, now IOP 22, you have 2 choices; go for 6-12 months monitoring progression
Or Add another medication (fixed combination PG + timolo)= one bottle, this might give 20 which is 35% reduction, OK for now
Resist prescribing the second bottle as much as you can, adherence drops significantly and side effects increase appreciably